The present invention relates to a method of feeding a wrapping machine with portions of wrapping material.
On wrapping machines for forming overwrappings of paper or transparent material about a succession of products, the products are fed successively to a transfer station where each product is inserted inside a folding seat together with a portion of wrapping material, which, as the product is inserted inside the seat, is folded into a U about the product and subsequently closed by folding devices cooperating with the seat to form a tubular wrapping about the product.
On known wrapping machines of the aforementioned type, the portions of wrapping material are normally formed from a continuous strip fed towards the transfer station by two opposed push rollers downstream from which are provided, in succession: a gumming device, in the case of paper material, for gumming given points on the opposite surface of the strip to that facing the folding seat; a cutting unit comprising a fixed blade and a movable blade, for cutting the strip into portions; and a guide device extending through the transfer station and comprising guide strips positioned contacting the opposite surface of the portions to that facing the folding seat and defining a transportation surface perpendicular to the direction in which the products are fed towards the folding seat.
Consequently, the wrapping material is pushed towards the transfer station and, what is more, is gummed on the side facing the guide strips.
A first drawback of the above method is the possibility of the leading edge of the continuous strip remaining attached to the fixed blade on the cutting unit, thus resulting in curling of the strip when it is pushed forward by the push rollers. Moreover, withdrawal of the portions, for any reason, from the transfer station inevitably results in fouling of the guide strips by the gum with which the portions are coated.